Modern bicycle design techniques have produced systems which bind the cycling shoe to the crank arm of the bicycle to allow the transmission of pushing as well as pulling pedalling efforts to the crank arm. With this system, the cyclist can supply a propelling force to the bicycle almost during the entire crank revolution, permitting the cyclist to achieve a considerable gain in efficiency in comparison to the more traditional approach where forward motion is communicated to the bicycle only by exerting a pushing effort on the pedals.
There are currently two general designs of such pedal systems. The most popular is the so-called "toeclip" system which incorporates a cage tightly enclosing the toe portion of the cycling shoe and a cleat with a transverse channel which locks into the pedal as well as a strap for holding the cage and the shoe together. The other design, referred to as "clipless" system uses a pair of cooperating members provided on the pedal and on the sole of the cycling shoe respectively, which interlock and prevent separation between the pedals and the cycling shoe under normal pedalling efforts.
Both pedal systems do not allow the cyclist to readily change the longitudinal position of the foot with respect to the pedal pivot axis. With the "clipless" system, changing the foot position requires loosening of fasteners, and accordingly, this operation cannot be performed while bicycling. As a result, the system must be set for the optimum foot position selected in accordance with various factors such as the type of track or course on which the bicycle is to be used. In most instances, the selected foot position constitutes only a compromise between the various ideal foot positions for the different track sections.
It has been suggested in the past to provide the "toeclip" system with a mechanism for longitudinally changing the foot position with respect to the pedal pivot axis via multiple transverse channels in the cleat while bicycling. However, the operation is complex to perform, still requires removal of the cycling shoe from the pedal, and with the available systems, only a limited range of adjustability is possible due toeclip clip size limitations. In addition, when at high speeds and on rough roads, performing this readjustment while bicycling can produce a loss of balance from the foot slipping off the pedal, and subsequent injury.